Padlocks are typically used for securing possessions, such as bicycles, trailers etc against theft whilst their owners are absent, or for preventing unauthorised access to particular areas or locations.
However, padlocks generally do not present a significant barrier to a person seriously intent on theft or trespass. In this regard, even a moderately well equipped thief or trespasser usually possesses the wherewithal to sever or force the shackle of the padlock.
There are a number of known padlocks which include an integral alarm system adopted to sound or activate when the padlock is violated or tampered with. Representative of such prior art padlocks are those decribed in U.S. Pat. No. 3,993,987, 4,556,872 and 4,811,578.
All of the padlocks disclosed in the above U.S. Patent Specifications include an audible alarm sounding device, a battery for energizing the audible alarm sounding device and an electrical circuit having switches connecting the audible alarm sounding device to the battery for actuation when the padlock is tampered with or violated. A problem associated with all battery operated equipment is that the battery or batteries eventually wear out and, if use of the alarm function is to continue, must be replaced.
The padlocks described in the above noted U.S. Patent Specifications each include provision for access to the battery housed within the padlock body to enable removal and replacement. In each, however, such provision affords an obvious point at which to gain unauthorised access to the battery, remove it and thereby deactivate or disable the alarm.
It is an object of the present invention to provide a padlock incorporating a tamper alarm having features which reduce to at least some extent, as compared with the prior art, the opportunity for unauthorised deactivation of the tamper alarm.